Hydraulic system for supplying pressure liquid to motors of hydraulic machines



June 24, 1952 TOWLER ET AL 2,601,675

HYDRAULIC SYSTEM FOR SUPPLYING PRESSURE LIQUID TO MOTORS OF HYDRAULIC MACHINES Filed May 15, 1946 3 Sheets-Sheet l Inventor M0 M 2:: Mp4.

June 1952 J. M. TOWLER ET AL 2,601,675

HYDRAULIC SYSTEM FOR SUPPLYING PRESSURE LIQUID TO MOTORS OF HYDRAULIC MACHINES Filed May 15, 1946 5 Sheets-Sheet 2 4 Inventor W M I Allorne June 1952 J. M. TOWLER ET AL 2,601,675

HYDRAULIC SYSTEM FOR SUPPLYING PRESSURE LIQUID TO MOTORS OF HYDRAULIC MACHINES Filed May 15, 1946 3 Sheets-Sheet 3 EXHAUST PRESSURE LINE T0 HYDRAUL/C MOTOR 77 Inventor MM Attorney Patented June 24, 1952 UNITED STATES PATENT OFFICE HYDRAULIC. SYSTEM FOR. SUPBIQYlNQ PRESSURE L o UIn o MOTORS F HYDRAULIC MACHINES John Maui-ice Towler, Harro'gate; and Frank- Hathorn Towler, otley, England; assignors to Electraulic Presses Limited; Rodley, near Leeds,

England; a corporation of England Application May 15, 1946, Serial No, 669358 In Great Britain May 25, 1945 the kindin which a continuously running high speed pump is used to supply pressure liquid. to actuate a hydraulic press under the control of an automatically operating valve.

In practice it is foundthata fluctuating. pressure occurs in the pressure supply main to the press and it is the object eithe present invention to overcome this trouble in a simple and reliable manner.

The improved system according: to the present invention comprises in combination a con-time cu'sly runniii'g high-speedpump, an automatically operating unloading valve for unloading the pump chambers when the pressure the delivery'mam reaches a predetermiued maxinium, a mastereonltr'ol valve actuated by the pressure in the pump deliverymairr to supply liquid at a lower pressure foractuatihg the unloading valve and interposed between the pump delivery and the press or other hydraulic machine to be actuated, and a reducingvalve interposed in the-main pressure line between the outlet of' the master control-valve and; the ir rlet of the press or other hydraulic cylinder.

To enable the invention to be understood and carried into effect an arrangement of: apparatus forming a practical embodiment otthe improved will now be described by aid of the accompanylngfigures, which:

Fig. I is'a sectional view of the filiid suppl y arid the unloading valve for controlling the pump output;

Fig. 2 is a sectional vievvof the master control valve interposed. between the supply pump and the reducing valve.

Fig. his a sectional view of the reducin valve included iii the hydraulic circuit between. the master control valve and the hydraulic press.

The system illustrated in the drawing comprises a high speed multl-ram reciprocating. pump A adapted for continuous runningarr automatically operatingvalve B for unloadihg the-pumpchambers of the pump A whenthe pressure in the: delivery main: reaches apredetermined maximum, amaster control valve 0 adapted to be actuated the ressure iii the: pump delivery main" to supply liquid at alower'pressure' for actuation of the unloading: valve B, and: a reducing valve D arranged so as tor control the flow ofpressure liquid to a press: or other hydraulic apparatus.

will; be seen from. the drawings, the pump delivery main I is connected toithe pressure liquid inlet P9 of themaster control valve C by means or a pl-"pe 2*. The" pressure liquid inlet 31 of the unloading mm is connected with the reduced pressure outlet-4 of the master control valve by meaiisof pipe 5. The; high pressure liquid outlet 6 orthe ma ter control valve is connected to the inlet; 1 of the reducing valve by pipe 8.whilst a further pipe 9 connects the outlet ID of this re: ducing' valve to the hydraulic machine, for examplethe pressure supply main of one or more hydraulicpresses' (not shown). The unloading; valve B comprises an automatically operating plunger ll which is moved longitudinally and relative to a; dischargeoutlet [2 in the wall of each pump bore l3, said outlets 12- beingaclditional to the usual valve controlled pump discharge out-- lets l4, and. saidhlongitudinal movement being effected agairlsta spring 15. constitutinga predetermined load. For moving the plunger I l the pressure liquidis admitted to a space 16 and it there acts against a'piston ll and a ram l8, the piston being of. substantially larger area than the" ram on which itis mounted for independent relative movement-. With this arrange-- ment the first part ofthe plungers stroke is effected by the pressure liquid acting against the combined; area'sof the; piston I? and the ram l8 this movement is utilised,- in the illustrated example. to unload two' of the pump chambers. The unloading of the last or third pump chamber the seriesiseffected by the ram alone and this requires a substantial rise to occur in the pres: sure liquid before it cantake place owingto the much smaller areapresented to the pressure liquid by the ram than was presented by the combined areas of the piston and the ram which wasavailablefor imparting thefirstpart of the unloading stroke This enables the lastpump bore, or pump where separate pumps are under control; to be out and out rapidly to supply make-up liquid; to a hydraulic system, for example to counteract normal leakage, with the other pump chamber or pump' zremaimng unloaded.

The unloading valve". B described above con stitutes'l inpart the subject matter ofour United StatesiPatent No:- 2,4-'78 ,2 1-3; filed February l7; 1944, l'SSlIGdZAlIgHSl? 91 1949 The" master control valve which will bepresently described, constitutes in part the subject matter of our copending United States application Serial No. 522.844 filed February 1 7-, 1944, now Patent Nb. 2,561,431; issued July 24,. 1951-.

The master control valve C- as illustrated corripr-ises an" inlet 19', withwhicli the outlet 6 has freecommunication through the intermediary of an annulus 20, an orifice- 40, and a non-return valve 21.

Within. the; valve body. and surrounded 5v 3 annular chambers 26 and 25 is a bore 26 for the reception, in a close sliding fit, of a valve plunger 21. The annular chambers 25 and 25 are in communication with the interior of the bore 26 by means of two sets of radial passages, one set 28 connecting the bore with the lower annular chamber 20 and the other set 23 connecting the bore with the upper annular chamber sition. In passing from the chamber 25 to the exhaust outlet 23 the fluid goes through passages 30, the upper end of bore 26, space 43, the duct 4|. the circular passage 42 around the cylinder 44 of the pressure relief valve 22, and the conduit 45.

Annular grooves 46 and 41 are cut in the exterior surface of the valve plunger 21 so as to encircle the same. These grooves are spaced longitudinally a distance equivalent to the distance between the centers of the sets of radial passages 28 and 29 with which they are adapted to register when the valve plunger is in the raised or open position shown in Fig. 2. The grooves 46 and 41 communicate with a longitudinal passage 49 within the interior of the valve plunger 21 by means of radial holes 56 and 5|. By this means a passage for liquid is provided between the annular chambers and when the valve plunger is in the raised position and said chambers are isolated from each other when the valve plunger is in the lowered position. Because of the symmetrical location of the fluid chambers the plunger 21 is always in hydraulic balance laterally.

At opposite ends of the valve plunger 21 are spaces 43 and 52 which are always in free communication with the exhaust outlet 23. The communication passage for space 43 is through the duct 4|, the circular passage 42, and the conduit 45. The conduit 54 forms a communication passage between space 52 and exhaust outlet 23. It is apparent that the interconnection of the spaces 43 and 52 with the exhaust outlet 23 will produce equal pressures in the spaces, thereby tending to place the plunger 21 in hydraulic balance longitudinally. The space 43 is closed at the upper end by a suitable packin 39. l

%n Fig. 2 the valve plunger 21 is shown in the raised position and passing liquid at a predetermined pressure from the pump to the auxiliary apparatus. The movement of the plunger to the raised position is effected against the spring 55 by pressure liquid acting upon the lower or full pressure side of piston 56. The piston stem 51 enters the space 52 and abuts against the lower end 59 of the valve plunger 21.

The pressure liquid which acts against the under side of the piston 56 is supplied through the one-way valve 2| from the annular chamber 20. This pressure liquid is routed to both sides of the piston 56 in the cylinder 60 in which the piston reciprocates. Conduits 6| and 62. carry fluid to the upper end of the piston 56 and conduits 6| and 64 channel fluid to the lower end of the piston 56. A non-return valve 66'is positioned in the conduit 64 to pass liquid freely to the under side of the piston 56. When pressure in the conduit 6| falls, the influence of. the spring 61 will cause the valve 66 to close automatically and prevent liquid from escaping I from the lower end of the cylinder 60. The liquid thus trapped below the piston 56 is permitted to escape at a relatively slow rate by leakage between the piston 56 and the side walls 66 of the cylinder to the upper end of the cylinder 60. Sufficient clearance is provided between the piston 56 and the cylinder wall 60 to permit liquid to escape past the piston 56 so that the piston and the plunger 21 will descend under the influence of the spring 55 at the desired rate.

By means of the arrangement just described, the pressure liquid is permitted to act against the effective area of the piston 56 equal to the area of the stem 51. When this pressure is sufficient to overcome the resistance of the spring 55, the valve plunger 21 is forced upwardly to the position illustrated in Fig. 2. By thus permitting the pressure liquid from the valve inlet l9 to have free access to the under side of the piston 56, the valve plunger 21 is rendered fully sensitive to and is immediately actuated by a sudden increase in the pressure of the said liquid. By restricting the escape of the liquid from the under side of piston 56 as previously described, the return movement of the valve plunger 21 and the spring 55 is damped to minimize hunting caused by increases and decreases of the fluid at the inlet l9 and in the conduits 6|. 1

When the plunger 21 is in the raised position, illustrated in Fig. 2, pressure liquid is free to pass to the outlet 4 and at the same time the relief valve 22 is subject to its pressure. The path of the liquid from the inlet l9 to the outlet 4 and the relief valve 22 is through the annulus 20, radial passage 28, annular groove 41, radial hole 50 in the plunger 21, longitudinal passage 49, radial hole 5|, annular groove 46, radial passages 29, and annular chamber 25. The chamber 25 communicates with outlet 4 and relief valve 22 through channels 9| and 92 respectively. By suitably setting this relief valve it is able to blow-off at a predetermined pressure below the pressure of the liquid at the inlet Hi. This master control valve thus supplies to the unloading valve for its operation, pressure liquid at any required pressure below the delivery pressure in the pump delivery main.

The example of reducing valve illustrated in the accompanying drawing comprises a spring pressed plunger 3|, shown in the partlyraised position, having a reduced portion3|c in it's length which, when the plunger is in the normal lowered position bridges passages 69 and 10 connecting the inlet 1 and outlet |0. A space 32 at'the bottom of the plunger is in open communication through bores 1|, 12 and 13 with the pressure inlet 1. A counterbore 1B is pro: vided through which bores 1| and 12 are interconnected. When this liquid which presses up wardly on the lower end of plunger 3|attains a pressure sufiicient to overcome thedownward pressure of the spring pressed plunger said plunger is forced upwards to isolate the inlet 1 from the outlet IE] and to open the inlet to exhaust. The exhaust fluid flows through passage 69, the annularspace 14 between thereduced portion 3|a of the plunger 3| and the cylindrical opening 15 in which the plunger reciprocates, the radial outlets 16 and the circular clearance space 11 between the lower spring seat 19 and the inside diameter B6 of the upper casing 8|, into the'enclosed space 82 of the upper casing 8|. From this space the exhaust fluid is ree t pass aroundth iupn r Shr ne suiflciently the: plunger moves downwards under influence of spring" 87 toreopenthe communication between the aforesaid inlet 1 and outlet i; Some of the fluid in the space32 below the plunger 3! is displaced by thedownward movement of the plunger II. This fluid flows back through the-hoses 13, 12, and H to the inlet 1 where it travels through the valve along with additional fluid entering through inlet 1. By, this (means the pressure of the liquid passing out through the outlet I0 is maintained substantially constant. Itis evident that the pressure to which the liquid at the outlet I0 is reduced is determined by the pressure required to raise the plunger tl against the spring 81. This latter pressure and hence the outlet pressure may be adjusted by meansof'the adjusting screw 88 provided in-the upperend of the casing 8|. This screw determines the position of the upper spring seat 84 to regulate the residual pressure of thespring 81 on the plunger 3 I. Adjustment of the screw determines the maximum pressure that may bedelivered to the hydraulic maohinethrough pipe 9. A suitable protective cap 90 is provided for covering the upper end of the screw 89.

We claim:

1. A hydraulic system comprising, in combination, a fluid motor, a continuously running pump for supplying fluid under pressure, means forming a supply passage interconnecting said pump and said motor to conduct fluid under pressure from said pump to said motor for actuating said motor, a plurality of pump chambers in said pump in communication with said supply passage, an unloading valve associated with said pump chambers for controlling the output of said pump by unloading at least one of said chambers in response to a predetermined fluid pressure, a pressure responsive master control valve interposed in said supply passage, said master control valve constituting means operable upon attainment of a predetermined pressure in said supply passage for diverting fluid at less than the maximum pump discharge pressure from said supply passage to said unloading valve for actuating said unloading valve to control the output of said pump, and a pressure reducing valve interposed in said supply passage between said master control valve and said fluid motor.

2. A hydraulic system of the kind specified, comprising in combination with a hydraulic motor, a high speed multi-ram pump having plural chambers and adapted to run continuously for supplying liquid for actuating said hydraulic motor, a main pressure line interconnecting said pump chambers and said hydraulic motor, an automatically operating unloading valve for unloading the respective pump chambers when the pressure in said main pressure line therefor reaches a predetermined maximum, said unloading valve being operable to unload at least one of the pump chambers at diiierent time relation with respect to the others and under different pressure values, a master control valve actuated by the pressure in the pump delivery main, said control valve constituting means for diverting liquid to said unloading valve at a lower pressure than the maximum pump delivery pressure for actuating the unloading valve, said master control valve being thepump delivery and the hydraulic motor to" to unload at least one of said pump chan-lbersv at difierent time relation with respect to the others and under different pressure values, a control valve actuated by the pressure in the pump delivery main to divert liquid from said delivery main to said unloading valve for actuating said unloading, valve, said control valve being interposedin the delivers main between the pump delivery and the hydraulic motor to be actuated, and a pressure reducingyalve interposed in the delivery main between the control valve and'the hydraulic motor.

4. A fluid system comprising in combination, a fluid motor, a fluid pump for supplying actuating fluid to said motor, a plurality of chambers in said pump, means defining a fluid pas,- sageway between said chambers and said motor, an unloading valve having exhaust ports corresponding in number to the number of said chambers, said exhaust ports being paired with said chambers with each port communicating with a single chamber, a control member associated with said exhaust ports for cont-rolling said pump by unloading any number of said chambers, a pressure responsive control valve interposed in said fluid passageway, said control valve constituting means for diverting fluid from said passageway to said control member for controlling said pump, and a pressure reducing valve interposed in said fluid passageway between said control valve and said fluid motor.

5. A hydraulic system comprising, in combination, a continuously running pump for supplying fluid under pressure to a fluid motor, means defining a supply passage for conducting fluid under pressure from said pump for delivery to said motor, said pump having a plurality of pump chambers in delivery communication with said passage, an unloading valve associated with said pump chambers and operable normally to maintain said pump chambers loaded and operable in response to a predetermined rising pressure gradient successively to unload said chambers whereby to control the output of said pump, a master control valve interposed in said supply passage and having a fluid diverting outlet and being responsive to the pressure in said passage to divert fluid from said passage to said outlet upon the attainment of pressure above a predetermined pressure in said supply passage, and a control passage interconnecting said outlet and said unloading valve for transmitting the pressure of diverted fluid to act on said unloading valve, said control valve also being operable to relieve the pressure in said control passage upon a drop in pressure in said supply passage below said predetermined pressure.

6. A hydraulic system for supplying fluid interposed in said main pressure line between under pressure to a hydraulic motor, comprising,

in combination, a hydraulic pump having a plurality of pump chambers and a delivery out-' let, a supply passage for conducting fluid from said outlet and adapted for connection to said motor, an unloading valve associated with said pump chamber and having pressure. responsive control means operable to unload at least one of said chambers upon being subjected to a first predetermined elevated pressure and to unload said one and still another of said chambers upon being subjected to a higher second predetermined pressure and'operable to effect loading of said chambers in reverse order upon being subjected to pressures dropping progressively below said predetermined pressures, means defining a control passage connected to said unloading valve to transmit pressure to said control means, and a master control valve interposed in said supply passage, said control valve permitting the flow of fluid past it through said supply passage and having means defining a diverting passage'connected to said control passage and control means normally tending to close said diverting passage and responsive to the pressure in said supply passage to open said diverting passage upon the attainment of a third predetermined pressure in said supply passage and successively to close said diverting passage and vent said control assage to exhaust upon a progressive drop in pressure below said third predetermined pressure. 7. A hydraulic system according to claim 6 including a pressure reducing valve interposed in said supply passage at the downstream side of said control valve. 7 JOHN MAURICE TOWLER. FRANK HATHORN TOWLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

